Targeted long-read sequencing identifies missing disease-causing variation.
Despite widespread clinical genetic testing, many individuals with suspected genetic conditions lack a precise diagnosis, limiting their opportunity to take advantage of state-of-the-art treatments. In some cases, testing reveals difficult-to-evaluate structural differences, candidate variants that do not fully explain the phenotype, single pathogenic variants in recessive disorders, or no variants in genes of interest. Thus, there is a need for better tools to identify a precise genetic diagnosis in individuals when conventional testing approaches have been exhausted. We performed targeted long-read sequencing (T-LRS) using adaptive sampling on the Oxford Nanopore platform on 40 individuals, 10 of whom lacked a complete molecular diagnosis. We computationally targeted up to 151 Mbp of sequence per individual and searched for pathogenic substitutions, structural variants, and methylation differences using a single data source. We detected all genomic aberrations-including single-nucleotide variants, copy number changes, repeat expansions, and methylation differences-identified by prior clinical testing. In 8/8 individuals with complex structural rearrangements, T-LRS enabled more precise resolution of the mutation, leading to changes in clinical management in one case. In ten individuals with suspected Mendelian conditions lacking a precise genetic diagnosis, T-LRS identified pathogenic or likely pathogenic variants in six and variants of uncertain significance in two others. T-LRS accurately identifies pathogenic structural variants, resolves complex rearrangements, and identifies Mendelian variants not detected by other technologies. T-LRS represents an efficient and cost-effective strategy to evaluate high-priority genes and regions or complex clinical testing results.
Miller, DE; Sulovari, A; Wang, T; Loucks, H; Hoekzema, K; Munson, KM; Lewis, AP; Fuerte, EPA; Paschal, CR; Walsh, T; Thies, J; Bennett, JT; Glass, I; Dipple, KM; Patterson, K; Bonkowski, ES; Nelson, Z; Squire, A; Sikes, M; Beckman, E; Bennett, RL; Earl, D; Lee, W; Allikmets, R; Perlman, SJ; Chow, P; Hing, AV; Wenger, TL; Adam, MP; Sun, A; Lam, C; Chang, I; Zou, X; Austin, SL; Huggins, E; Safi, A; Iyengar, AK; Reddy, TE; Majoros, WH; Allen, AS; Crawford, GE; Kishnani, PS; University of Washington Center for Mendelian Genomics, ; King, M-C; Cherry, T; Chong, JX; Bamshad, MJ; Nickerson, DA; Mefford, HC; Doherty, D; Eichler, EE
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